بعد التمرين حسيت بوجع بظهري وببطني، فقررت ارتاح اليوم.

It means after the workout / after exercising.

A few notes:

• بعد = after
• التمرين = the exercise, the workout, the training session, or the practice

So depending on context, التمرين could mean:

• a gym workout
• a training session
• practice
• an exercise or drill

In this sentence, after the workout or after exercising is the most natural reading.

Because Arabic usually does not need the subject pronoun if the verb already shows who the subject is.

Here:

• حسيت already means I felt
• قررت already means I decided

So أنا is optional. You could say أنا حسيت... if you want emphasis, but it is not necessary.

Yes. حسيت is a colloquial Levantine way to say I felt.

It comes from the verb حسّ / يحسّ = to feel, to sense.

In more formal Arabic, you would more often see شعرتُ for I felt.

So:

• حسيت = colloquial, very common in speech
• شعرتُ = more formal / Modern Standard Arabic

Because in Levantine, the verb حسّ often takes بـ before the thing you feel.

So:

• حسيت بوجع = I felt pain

This is just the normal pattern in colloquial Arabic. English says I felt pain, but Levantine often says something closer to I felt with pain structurally, even though that is not how you should translate it.

وجع means pain, ache, or soreness. It is very common in everyday spoken Arabic.

Compared with ألم:

• وجع = more colloquial, everyday speech
• ألم = more formal, more literary, more medical-sounding

So in natural Levantine conversation, وجع is very normal here.

Here بـ marks the location of the pain, so it means something like in or in my.

So:

• بظهري = in my back
• ببطني = in my stomach / in my belly / in my abdomen

This is very natural in Levantine when talking about pain in body parts.

So the structure is:

• حسيت بوجع = I felt pain
• بظهري وببطني = in my back and in my stomach

The ending -ي means my.

So:

• ظهر = back
• ظهري = my back

and:

• بطن = stomach / belly / abdomen
• بطني = my stomach / my belly

This is how Arabic often shows possession: by attaching a pronoun directly to the noun.

Because Arabic often repeats the preposition with each item in a list, especially when it sounds clearer or more natural.

So:

• بظهري وببطني = in my back and in my stomach

You may sometimes hear less repetition in other contexts, but here repeating بـ sounds very normal.

It can mean several close things:

• my stomach
• my belly
• my abdomen

In everyday English, my stomach is probably the most natural translation, but my belly can also fit depending on tone.

فقررت means so I decided or then I decided.

Breakdown:

• فـ = so, then, therefore
• قررت = I decided

The فـ is attached directly to the verb because it is a very common Arabic connector.

So the sentence flows like:

• I felt pain in my back and stomach, so I decided to rest today.

Because in Levantine, after verbs like decided, speakers often use the imperfect verb directly, without أن.

So:

• قررت ارتاح = I decided to rest

In more formal Arabic, you are more likely to see:

• قررت أن أرتاح

Both express the same basic idea, but the version in your sentence is more colloquial and natural in Levantine speech.

In casual colloquial writing, people often do not write hamzas very carefully.

So ارتاح here is understood as أرتاح = I rest / I will rest in this context.

This is very common in texting and informal writing. In more careful spelling, especially in formal Arabic, you would usually write أرتاح.

Because after I decided, Arabic often uses the imperfect verb to express the action decided on.

So:

• قررت ارتاح = I decided to rest

This is similar to how English uses the infinitive after decided.

Arabic does not always use a separate infinitive the way English does, so the imperfect verb often fills that role in colloquial speech.

Yes. This exact sentence works for both.

That is because in the first person singular in the past tense, the forms are the same for male and female speakers:

• حسيت = I felt
• قررت = I decided

So whether the speaker is a man or a woman, the sentence does not need to change.

Yes, it sounds clearly colloquial and fits Levantine very well.

Features that make it colloquial include:

• حسيت instead of شعرت
• وجع instead of the more formal ألم
• قررت ارتاح instead of قررت أن أرتاح

A more formal version could be:

بعد التمرين شعرتُ بألمٍ في ظهري وبطني، فقررتُ أن أرتاح اليوم.

That is more like Modern Standard Arabic, while your original sentence sounds natural in everyday Levantine.

Yes, you could, but it changes the nuance a little.

• حسيت بوجع... = I felt pain...
• عندي وجع... = I have pain...

The sentence you were given focuses on the experience right after the workout: I felt pain, so it sounds tied to that moment.

Using عندي وجع sounds more like describing your current condition: I have pain in my back and stomach.

Both are natural, but they are not exactly the same in feel.